NAME¶

DESCRIPTION¶

GLOBAL PART¶

logdir = Directory

All Yaws logs will be written to files in this directory. There are several different log files written by Yaws:

 

report.log - this is a text file that contains all error logger printouts from Yaws.

 

<Host>.access - for each virtual host served by Yaws, a file <Host>.access will be written which contains an access log in Common Log Format. (See http://en.wikipedia.org/wiki/Common_Log_Format for more details on Common Log Format.)

 

<Host>.auth - for each virtual host served by Yaws, a file <Host>.auth will be written which contains all http auth related messages.

 

trace_<YYYYMMDD_hhmmss> - Trace files are written in this subdirectory, suffixed by the creation date.

 

ebin_dir = Directory

This directive adds Directory to the Erlang search path. It is possible to have several of these commands in the configuration file. The default value is "yaws_dir"/examples/ebin

 

 

id = String

It is possible run multiple Yaws servers on the same machine. We use the id of a Yaws server to control it using the different control commands such as:

 

  # /usr/local/bin/yaws --id foobar --stop
    

 

To stop the Yaws server with id "foobar". Each Yaws server will write its internals data into a file called $HOME/.yaws/yaws/ID where ID is the identity of the server. Yaws also creates a file called ${VARDIR}/run/yaws/ctl-${ID} which contain the port number where the server is listening for control commands. The default id is "default".

 

server_signature = String

This directive sets the "Server: " output header to the custom value. The default value is "yaws/%VSN%, Yet Another Web Server".

 

include_dir = Directory

This directive adds Directory to the path of directories where the Erlang compiler searches for include files. We need to use this if we want to include .hrl files in our Yaws Erlang code. It is possible to have several of these commands in the configuration file. The default value is "yaws_dir"/examples/include.

 

max_num_cached_files = Integer

Yaws will cache small files such as commonly accessed GIF images in RAM. This directive sets a maximum number on the number of cached files. The default value is 400.

 

max_num_cached_bytes = Integer

This directive controls the total amount of RAM which can maximally be used for cached RAM files. The default value is 1000000, 1 megabyte.

 

max_size_cached_file = Integer

This directive sets a maximum size on the files that are RAM cached by Yaws. The default value is 8000, 8 kBytes.

 

cache_refresh_secs = Integer

The RAM cache is used to serve pages that sit in the cache. An entry sits in cache at most cache_refresh_secs number of seconds. The default is 30. This means that when the content is updated under the docroot, that change doesn't show until 30 seconds have passed. While developing a Yaws site, it may be convenient to set this value to 0. If the debug flag (-d) is passed to the Yaws start script, this value is automatically set to 0.

 

trace = false | traffic | http

This enables traffic or http tracing. Tracing is also possible to enable with a command line flag to Yaws. Default is false.

 

use_old_ssl = true | false

This re-enables the old OTP ssl implementation. By default we use the new ssl implementation.

 

auth_log = true | false

Deprecated and ignored. Now, this target must be set in server part.

 

max_connections = nolimit | Integer

Set this value to control the maximum number of connections from HTTP clients into the server. This is implemented by closing the last socket if the limit threshold is reached.

 

keepalive_maxuses = nolimit | Integer

Normally, Yaws does not restrict the number of times a connection is kept alive using keepalive. Setting this parameter to an integer X will ensure that connections are closed once they have been used X times. This can be a useful to guard against long running connections collecting too much garbage in the Erlang VM.

 

process_options = undefined | Proplist

Set process spawn options for client acceptor processes. Options must be specified as a quoted string of either the atom undefined or as a proplist of valid process options. The supported options are fullsweep_after, min_heap_size, and min_bin_vheap_size, each taking an associated integer value. Other process options are ignored. The proplist may also be empty. See erlang:spawn_opt/4 for details on these options.

 

acceptor_pool_size = Integer

Set the size of the pool of cached acceptor processes. The specified value must be greater than or equal to 0. The default value is 8. Specifying a value of 0 effectively disables the process pool.

 

log_wrap_size = Integer

The logs written by Yaws are all wrap logs, the default value at the size where they wrap around and the original gets renamed to File.old is 1000000, 1 megabyte. This value can be changed.

 

If we set the value to 0 the logs will never wrap. If we want to use Yaws in combination with a more traditional log wrapper such as logrotate, set the size to 0 and Yaws will reopen the logfiles once they have be renamed/removed.

 

log_resolve_hostname = true | false

By default the client host IP is not resolved in the access logs.

 

 

fail_on_bind_err = true | false

Fail completely or not if Yaws fails to bind a listen socket Default is true.

 

enable_soap = true | false

If true, a soap server will be started at startup of Yaws. Default is false.

 

soap_srv_mods = ListOfModuleSetting

If enable_soap is true, a startup Yaws will invoke yaws_soap_srv:setup() to setup modules set here. ModuleSetting is either a triad like <Mod, HandlerFunc, WsdlFile> or a quadruple form like <Mod, HandlerFunc, WsdlFile, Prefix> which specifies the prefix. A prefix will be used as argument of yaws_soap_lib:initModel() and then be used as a XML namespace prefix. Note, the WsdlFile here should be an absolute-path file in local file systems.

 

For example, we can specify

 

  soap_srv_mods=<Mod1, HandlerFunc, WsdlFile1> <Mod2, HandlerFunc, WsdlFile2, SpecifiedPrefix> ...
    

 

php_exe_path = Path

this target is deprecated and useless. use 'php_handler' target in server part instead.

 

The name of (and possibly path to) the php executable used to interpret php scripts (if allowed). Default is php_exe_path = php-cgi.

 

copy_error_log = true | false

Enable or disable copying of the error log. When we run in embedded mode, there may very well be some other systems process that is responsible for writing the errorlog to a file whereas when we run in normal standalone mode, we typically want the Erlang errorlog written to a report.log file. Default value is true.

 

ysession_mod = Module

Allows to specify a different Yaws session storage mechanism instead of an ETS table. One of the drawbacks of the default yaws_session_server implementation is that server side cookies are lost when the server restarts. Specifying a different module here will pass all writes/read operations to this module (it must implements appropriate callbacks).

 

runmod = ModuleName

At startup Yaws will invoke ModuleName:start() in a separate process. It is possible to have several runmods. This is useful if we want to reuse the Yaws startup shell script for our own application.

 

pick_first_virthost_on_nomatch = true | false

When Yaws gets a request, it extracts the Host: header from the client request to choose a virtual server amongst all servers with the same IP/Port pair. This configuration parameter decides whether Yaws should pick the first (as defined in the yaws.conf file) if no name match or not. In real live hosting scenarios we typically want this to be false whereas in testing/development scenarios it may be convenient to set it to true. Default is true.

 

keepalive_timeout = TimeInMilliseconds | infinity

If the HTTP session will be kept alive (i.e., not immediately closed) it will close after keepalive_timeout milliseconds unless a new request is received in that time. The default value is 30000. The value infinity is legal but not recommended.

 

 

subconfig = File

Load specified config file.

 

subconfigdir = Directory

Load all config file in specified directory.

 

x_forwarded_for_log_proxy_whitelist = ListOfUpstreamProxyServerIps

this target is deprecated and will be ignored.

 

SERVER PART¶

port = Port

This makes the server listen on Port. Default is 8000.

listen = IpAddress

This makes the server listen on IpAddress. When virthosting several servers on the same ip/port address, if the browser doesn't send a Host: field, Yaws will pick the first server specified in the config file. If the specified IP address is 0.0.0.0 Yaws will listen on all local IP addresses on the specified port. Default is 0.0.0.0. Multiple listen directives may be used to specify several addresses to listen on.

 

listen_backlog = Integer

This sets the TCP listen backlog for the server to define the maximum length the queue of pending connections may grow to. The default is the same as the default provided by gen_tcp:listen/2, which is 5.

 

server_signature = String

This directive sets the "Server: " output header to the custom value and overloads the global one for this virtual server.

 

 

rhost = Host[:Port]

This forces all local redirects issued by the server to go to Host. This is useful when Yaws listens to a port which is different from the port that the user connects to. For example, running Yaws as a non-privileged user makes it impossible to listen to port 80, since that port can only be opened by a privileged user. Instead Yaws listens to a high port number port, 8000, and iptables are used to redirect traffic to port 80 to port 8000 (most NAT:ing firewalls will also do this for you).

 

rscheme = http | https

This forces all local redirects issued by the server to use this method. This is useful when an SSL off-loader, or stunnel, is used in front of Yaws.

 

auth_log = true | false

Enable or disable the auth log for this virtual server. Default is true.

 

access_log = true | false

Setting this directive to false turns of traffic logging for this virtual server. The default value is true.

 

logger_mod = Module

It is possible to set a special module that handles access and auth logging. The default is to log all web server traffic to <Host>.access and <Host>.auth files in the configured or default logdir.

 

This module must implement the behaviour yaws_logger. Default value is yaws_log.

 

The following functions should be exported:

 

Module:open_log(ServerName, Type, LogDir)

shaper = Module

Defines a module to control access to this virtual server. Access can be controlled based on the IP address of the client. It is also possible to throttles HTTP requests based on the client's download rate. This module must implement the behaviour yaws_shaper.

 

There is no such module configured by default.

 

dir_listings = true | true_nozip | false

Setting this directive to false disallows the automatic dir listing feature of Yaws. A status code 403 Forbidden will be sent. Set to true_nozip to avoid the auto-generated all.zip entries. Default is false.

 

extra_cgi_vars = .....

Add additional CGI or FastCGI variables. For example:

 

  <extra_cgi_vars dir='/path/to/some/scripts'>
    var = val
    ...
  </extra_cgi_vars>
    

 

statistics = true | false

Turns on/off statistics gathering for a virtual server. Default is false.

 

fcgi_app_server = Host:Port

The hostname and TCP port number of a FastCGI application server. The TCP port number is not optional. There is no default value.

 

fcgi_trace_protocol = true | false

Enable or disable tracing of FastCGI protocol messages as info log messages. Disabled by default.

 

fcgi_log_app_error = true | false

Enable or disable logging of application error messages (output to stderr and non-zero exit value). Disabled by default.

 

deflate = true | false

Turns on or off deflate compression for a server. Default is false.

 

 

<deflate> ... </deflate>

This begins and ends the deflate compression configuration for this server. The following items are allowed within a matching pair of <deflate> and </deflate> delimiters.

 

min_compress_size = nolimit | Integer

  mime_types = default image/*
  mime_types = application/xml application/xhtml+xml application/rss+xml

docroot = Directory ...

This makes the server serve all its content from Directory.

 

It is possible to pass a space-separated list of directories as docroot. If this is the case, the various directories will be searched in order for the requested file. This also works with the ssi and yssi constructs where the full list of directories will be searched for files to ssi/yssi include. Multiple docroot directives can be used. You need at least one valid docroot, invalid docroots are skipped with their associated auth structures.

 

auth_skip_docroot = true | false

If true, the docroot will not be searched for .yaws_auth files. This is useful when the docroot is quite large and the time to search it is prohibitive when Yaws starts up. Defaults to false.

 

partial_post_size = Integer | nolimit

When a Yaws file receives large POSTs, the amount of data received in each chunk is determined by the this parameter. The default value is 10240.

 

 

dav = true | false

Turns on the DAV protocol for this server. The dav support in Yaws is highly limited. If dav is turned on, .yaws processing of .yaws pages is turned off. Default is false. Setting it to nolimit is potentially dangerous. The socket read timeout is supplied by the keepalive_timeout setting. If the read is not done within the timeout, the POST will fail.

 

tilde_expand = true|false

If this value is set to false Yaws will never do tilde expansion. The default is false. tilde_expansion is the mechanism whereby a URL on the form http://www.foo.com/~username is changed into a request where the docroot for that particular request is set to the directory ~username/public_html/.

 

allowed_scripts = ListOfSuffixes

The allowed script types for this server. Recognized are `yaws', `cgi', `fcgi', `php'. Default is allowed_scripts = yaws php cgi fcgi.

 

Note: for fcgi scripts, the FastCGI application server is only called if a local file with the .fcgi extension exists. However, the contents of the local .fcgi file are ignored.

 

tilde_allowed_scripts = ListOfSuffixes

The allowed script types for this server when executing files in a users public_html folder Recognized are `yaws', `cgi', `fcgi', `php'. Default is tilde_allowed_scripts = i.e. empty

 

 

appmods = ListOfModuleNames

If any the names in ListOfModuleNames appear as components in the path for a request, the path request parsing will terminate and that module will be called. There is also an alternate syntax for specifying the appmods if we don't want our internal erlang module names to be exposed in the URL paths. We can specify

 

  appmods = <Path1, Module1> <Path2, Modules2> ...
    

 

Assume for example that we have the URL http://www.hyber.org/myapp/foo/bar/baz?user=joe while we have the module foo defined as an appmod, the function foo:out(Arg) will be invoked instead of searching the filesystems below the point foo.

 

The Arg argument will have the missing path part supplied in its appmoddata field.

 

It is also possible to exclude certain directories from appmod processing. This is particulaly interesting for '/' appmods. Here is an example:

 

  appmods = </, myapp exclude_paths icons js top/static>
    

 

The above configuration will invoke the 'myapp' erlang module on everything except any file found in directories, 'icons', 'js' and 'top/static' relative to the docroot.

 

errormod_404 = Module

It is possible to set a special module that handles 404 Not Found messages. The function Module:out404(Arg, GC, SC) will be invoked. The arguments are

 

errormod_401 = Module

It is possible to set a special module that handles 401 Unauthorized messages. This can for example be used to display a login page instead. The function Module:out401(Arg, Auth, Realm) will be invoked. The arguments are

 

errormod_crash = Module

It is possible to set a special module that handles the HTML generation of server crash messages. The default is to display the entire formated crash message in the browser. This is good for debugging but not in production.

 

The function Module:crashmsg(Arg, SC, Str) will be called. The Str is the real crash message formated as a string.

 

The function must return, {content,MimeType,Cont} or {html, Str} or {ehtml, Term}. That data will be shipped to the client.

 

expires = ListOfExpires

Controls the setting of the Expires HTTP header and the max-age directive of the Cache-Control HTTP header in server responses for specific mime types. The expiration date can set to be relative to either the time the source file was last modified, or to the time of the client access. ListOfExpires is defined as follows:

 

  expires = <MimeType1, access+Seconds> <MimeType2, modify+Seconds> ...
    

 

These HTTP headers are an instruction to the client about the document's validity and persistence. If cached, the document may be fetched from the cache rather than from the source until this time has passed. After that, the cache copy is considered "expired" and invalid, and a new copy must be obtained from the source. Here is an example:

 

  expires = <image/gif, access+2592000> <image/png, access+2592000>
  expires = <image/jpeg, access+2592000> <text/css, access+2592000>
    

 

arg_rewrite_mod = Module

It is possible to install a module that rewrites all the Arg #arg{} records at an early stage in the Yaws server. This can be used to do various things such as checking a cookie, rewriting paths etc.

 

The module yaws_vdir can be used in case you want to serve static content that is not located in your docroot. See the example at the bottom of this man page for how to use the opaque + vdir elements to instruct the yaws_vdir module what paths to rewrite.

 

start_mod = Module

Defines a user provided callback module. At startup of the server, Module:start/1 will be called. The #sconf{} record (defined in yaws.hrl) will be used as the input argument. This makes it possible for a user application to synchronize the startup with the Yaws server as well as getting hold of user specific configuration data, see the explanation for the <opaque> context.

 

revproxy = Prefix Url [intercept_mod Module]

Make Yaws a reverse proxy. Prefix is a path inside our own docroot and Url argument is a URL pointing to a website we want to "mount" under the Prefix path. This example:

 

  revproxy = /tmp/foo http://yaws.hyber.org
    

 

makes the hyber website appear under /tmp/foo.

 

It is possible to have multiple reverse proxies inside the same server.

 

You can optionally configure an interception module for each reverse proxy, allowing your application to examine and modify requests and HTTP headers as they pass through the proxy from client to backend server and also examine and modify responses and HTTP headers as they return from the backend server through the proxy to the client.

 

You specify an interception module by including the optional intercept_mod keyword followed by Module, which should be the name of your interception module.

 

An interception module is expected to export two functions: rewrite_request/2 and rewrite_response/2. The two arguments passed to rewrite_request/2 function are a #http_request{} record and a #headers{} record, whereas rewrite_response/2 function takes a #http_response{} record and also a #headers{} record. You can find definitions for these record types in the yaws_api.hrl header file. Each function can examine each record instance and can either return each original instance or can return a modified copy of each instance in its response. The rewrite_request/2 function should return a tuple of the following form:

 

   {ok, #http_request{}, #headers{}}
    

 

and the rewrite_response/2 function should similarly return a tuple of the following form:

 

   {ok, #http_response{}, #headers{}}
    

 

A #headers{} record can easily be manipulated in an interceptor using the functions listed below:

 

   yaws_api:set_header/2, yaws_api:set_header/3
   yaws_api:get_header/2, yaws_api:get_header/3
   yaws_api:delete_header/2
    

 

Any failures in your interception module's functions will result in HTTP status code 500, indicating an internal server error.

 

fwdproxy = true|false

Make Yaws a forward proxy. By enabling this option you can use Yaws as a proxy for outgoing web traffic, typically by configuring the proxy settings in a web-browser to explicitly target Yaws as its proxy server.

 

servername = Name

If we're virthosting everal servers and want to force a server to match specific Host: headers we can do this with the "servername" directive. This name doesn't necessarily have to be the same as the the name inside <server Name> in certain NAT scenarios. Rarely used feature.

 

php_handler = <Type, Spec>

Set handler to interpret .php files. It can be one of the following definitions:

 

php_handler = <cgi, Filename> - The name of (and possibly path to) the php executable used to interpret php scripts (if allowed).

 

php_handler = <fcgi, Host:Port> - Use the specified fastcgi server to interpret .php files (if allowed).

 

  php5-cgi -b '127.0.0.1:54321'

  php_handler = <fcgi, 127.0.0.1:54321>

phpfcgi = Host:Port

this target is deprecated. use 'php_handler' target in server part instead.

 

Use this directive is same as: php_handler = <fcgi, Host:Port>.

 

<ssl> ... </ssl>

This begins and ends an SSL configuration for this server. It's possible to virthost several SSL servers on the same IP given that they all share the same certificate configuration. In general it is complicated to virthost several SSL servers on the same IP address since the certificate is typically bound to a domainname in the common name part of the certificate. One solution (the only?) to this problem is to have a certificate with multiple subjectAltNames. See http://wiki.cacert.org/VhostTaskForce#Interoperability_Test

 

keyfile = File

<redirect> ... </redirect>

Defines a redirect mapping. The following items are allowed within a matching pair of <redirect> and </redirect> delimiters.

 

We can have a series of Path = URL or Path = file

 

All accesses to Path will be redirected to URL/Path or alternatively to scheme:host:port/file/Path if a file is used. Note that the original path is appended to the redirected url. So if we for example have:

 

  <redirect>
    /foo = http://www.mysite.org/zapp
    /bar = /tomato.html
  </redirect>
    

 

Asumming this config resides on a site called http://abc.com, We have the following redirects:

 

  http://abc.com/foo -> http://www.mysite.org/zapp/foo

  http://abc.com/foo/test -> http://www.mysite.org/zapp/foo/test

  http://abc.com/bar -> http://abc.com/bar

  http://abc.com/bar/x/y/z -> http://abc.com/bar/x/y/z
    

 

Sometimes we do not want to have the original path appended to the redirected path. To get that behaviour we specify the config with '==' instead of '='.

 

  <redirect>
    /foo == http://www.mysite.org/zapp
    /bar = /tomato.html
  </redirect>
    

 

Now a request for http://abc.com/foo/x/y/z simply gets redirected to http://www.mysite.org/zapp. This is typically used when we simply want a static redirect at some place in the docroot.

 

When we specify a file as target for the redirect, the redir will be to the current http(s) server.

 

 

<auth> ... </auth>

Defines an auth structure. The following items are allowed within a matching pair of <auth> and </auth> delimiters.

 

docroot = Docroot

    {User, Password}.

  allow = 10.1.2.3
  allow = 192.168.1.104, 192.168.1.205

  allow = 10.1.0.0/255.255.0.0

  allow = 10.1.0.0/16

<opaque> ... </opaque>

This begins and ends an opaque configuration context for this server, where 'Key = Value' directives can be specified. These directives are ignored by Yaws (hence the name opaque), but can be accessed as a list of tuples {Key,Value} stored in the #sconf.opaque record entry. See also the description of the start_mod directive.

 

This mechanism can be used to pass data from a surrounding application into the individual .yaws pages.

 

 

 

 

EXAMPLES¶

    logdir = /var/log/yaws
    <server www.mydomain.org>
        port = 80
        listen = 192.168.128.31
        docroot = /var/yaws/www
    </server>

    logdir = /var/log/yaws
    <server www.mydomain.org>
        port = 80
        listen = 192.168.128.31
        docroot = /var/yaws/www
    </server>

    <server www.funky.org>
        port = 80
        listen = 192.168.128.31
        docroot = /var/yaws/www_funky_org
    </server>

    logdir = /var/log/yaws
    <server www.mydomain.org>
        port = 80
        listen = 192.168.128.31
        docroot = /var/yaws/www
        access_log = false
        <auth>
            dir = secret/dir1
            realm = foobar
            user = jonny:verysecretpwd
            user = benny:thequestion
            user = ronny:havinganamethatendswithy
       </auth>
    </server>

    <server www.funky.org>
        port = 80
        listen = 192.168.128.31
        docroot = /var/yaws/www_funky_org
        start_mod = btt
        <opaque>
                mydbdir = /tmp
                mylogdir = /tmp/log
        </opaque>
    </server>

    <server www.funky.org>
        port = 80
        listen = 192.168.128.31
        docroot = /var/yaws/www_funky_org
        start_mod = authmod_gssapi
        <auth>
                authmod = authmod_gssapi
                dir = secret/dir1
        </auth>
        <opaque>
                keytab = /etc/yaws/http.keytab
        </opaque>
    </server>

    logdir = /var/log/yaws
    max_num_cached_files = 8000
    max_num_cached_bytes = 6000000

    <server www.mydomain.org>
        port = 80
        listen = 192.168.128.31
        docroot = /var/yaws/www
    </server>

    <server www.funky.org>
        port = 80
        listen = 192.168.128.31
        docroot = /var/yaws/www_funky_org
    </server>

    <server www.funky.org>
        port = 443
        listen = 192.168.128.32
        docroot = /var/yaws/www_funky_org
        <ssl>
           keyfile = /etc/funky.key
           certfile = /etc/funky.cert
           password = gazonk
        </ssl>
    </server>

    <server server.domain>
        port = 80
        listen = 192.168.128.31
        docroot = /var/yaws/www
        arg_rewrite_mod = yaws_vdir
        <opaque>
            vdir = "/virtual1/ /usr/local/somewhere/notrelated/to/main/docroot"
            vdir = "/myapp/ /some/other/path can include/spaces"
            vdir = "/icons/  /usr/local/www/yaws/icons"
        </opaque>
    </server>

AUTHOR¶

SEE ALSO¶